Composite shaft

ABSTRACT

A composite shaft has sheets rolled. A number of the sheets is three or multiple of three. Widths of the sheets are substantially identical to a length of a circumference of the shaft. Each of the rolled sheets has an overlapped rib distributed on the circumference of the shaft, and central angles between two of the neighboring ribs are substantially identical. The shaft of the present invention has a well mechanical strength and balance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a composite shaft, and more particularly to a composite shaft for golf club, ski stick, climbing stick, and fishing rod etc., which uniformly distributes vibration on entire shaft.

2. Description of the Related Art

Conventional composite shafts are made of carbon fiber, glass fiber or boron fiber prepreg resin, such as epoxy, for tubular elements. The methods of making the composite shafts include filament winding method and sheet rolling method. The filament winding method is to wind single type fiber filaments prepreg resin on a rod, which usually is an elongated tapered iron rod. An orientation of the filament is between thirty degrees and sixty degrees. For example, the filament is wound on the rod from an end to the other end with +45 degrees orientation to form a layer on the rod, and then the filament is wound backwards with −45 degrees orientation to form another layer on the layer. The orientations of the layers are cross that reinforces the strength. The advantages of the filament winding method include uniform distribution of the fibers, without the overlapped rib and non-orientation in elasticity test. The elasticity test is to fix an end of the shaft and vibrate a free end of the shaft to measure the status of the swing. The disadvantage of the filament winding method is the orientation of the fiber cannot be 0 degree that orientation gives the shaft a best capacity of anti-flexibility. The sheet rolling method is to make sheets of fiber prepreg resin. The sheets have a predetermined fiber orientation respectively, such ad forty-five degrees, sixty degrees and 0 degree. The sheets with various fiber orientations are stacked, and the stacked sheets are rolled on an elongated tapered iron rod to form a tubular shaft. The advantages of the sheet rolling method include well strength because that the fiber orientations of each sheet may be designated. The disadvantage is the shaft made by the sheet rolling method having overlapped rib. The shaft is thicker at the overlapped rib that make the shaft has orientation, which means, in the elasticity test, the swings are different while the fixed location of the shaft is changed. As a result, the locations of the ribs affect the status of swing of the shaft. In conclusion, the filament winding method provides the shafts with strength lower than the shaft made by the sheet rolling method, but, it has non-orientation and a well balance.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a composite shaft, which has well mechanical strength and balance.

According to the objective of the present invention, a composite shaft has sheets rolled. A number of the sheets is three or multiple of three. Widths of the sheets are substantially identical to a length of a circumference of the shaft. Each of the rolled sheets has an overlapped rib distributed on the circumference of the shaft, and central angles between two of the neighboring ribs are substantially identical.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first preferred embodiment of the present invention;

FIG. 2 is a sectional view along 2-2 line of FIG. 1;

FIG. 3 is a flow chart of the first preferred embodiment of the present invention, and

FIG. 4 is a sectional view of a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 to 2, a shaft 10 of the first preferred embodiment of the present invention is made from fiber prepreg resin reinforced sheets 11. A number of the sheets 11 is three or a multiple of three. In the first preferred embodiment, the number of the sheets is six, and the sheets are made of carbon fiber prepreg epoxy. Each of the sheets 11 has a width substantially identical to a length of a circumference of the shaft 10, and the widths of the sheets 11 are gradually increased from the interior sheet to the exterior sheet. Each of the sheets 11 is rolled up to form an overlapped portion, which is defined as a rib 111, and the ribs 111 of the sheets are uniformly distributed on the circumference of the shaft 10, such that the shaft 10 has six ribs 111 at orientations of twelve clock, two clock, four clock, six clock, eight clock and ten clock. Central angles of the neighboring ribs 111 are sixty degrees. Therefore, the shaft 10 of the present invention has a uniform mechanical property. Orientations of the fibers in each sheets 11 may be ±45 degrees, ±60 degrees and 0 degree, and orientations of the ribs 111 are 0 degree. They provide the shaft 10 of the present invention a well mechanical strength.

As shown in FIG. 3, in the process of making the shaft of the present invention, the carbon fiber prepreg epoxy sheets a, b, c. . . , f are cut for predetermined shapes. The orientations of the fibers of the sheets a, b, c. . . , f are +45 degrees, −45 degrees, +60 degrees, −60 degrees, 0 degree and 0 degree respectively. The fifth sheet e is made of carbon fiber with 0 degree fiber orientation, and the sixth sheet f is made of transparent glass fiber with 0 degree fiber orientation. In operation, operator rolls the sheets on a cone iron rod 20 with a scale or a mark 21 at an end or two opposite ends in sequence. The scale or the mark gives an index to separate the locations of the ribs. And then, heating the iron rod 20 with the sheets rolled thereon for curing, and after heating and the sheets are cooled, drawing the iron rod 20 out of the sheets to have a hollow shaft of the present invention.

It has to be mentioned that the number of the sheets of the present invention may be three with ±45 degrees and 0 degree or ±60 degrees and 0 degree fiber orientations, as shown in FIG. 4. The preferred number is six, but nine, twelve or twenty-fourth sheets are workable also. The conventional sheet rolling method usually reinforces the shaft at predetermined portions, such as tip, it also may be incorporated in the present invention. The shaft of the present invention may be made to golf club shaft, ski stick, climbing stick, and fishing rod etc. 

1. A composite shaft having sheets rolled, which a number of the sheets is three or multiple of three, wherein widths of the sheets are substantially identical to a length of a circumference of the shaft, and each of the rolled sheets has an overlapped rib distributed on the circumference of the shaft, and central angles between two of the neighboring ribs are substantially identical.
 2. The method of making a composite shaft, comprising the steps of: 1) making composite sheets for rolling, wherein widths of the sheets are substantially identical to a length of a circumference of the shaft; 2) rolling the sheets on a rod in sequence, wherein a number of the sheets is three or multiple of three, and each of the rolled sheets has an overlapped rib distributed on the circumference of the shaft, and central angles between two of the neighboring ribs are substantially identical; 3) heating the sheets with the rod for curing, and 4) removing the rod from the sheets to have the shaft.
 3. The method as defined in claim 2, wherein the rod has a scale or a mark at an end or at two opposite ends. 